Need assistance - TRAC codes 48 and 51 - 1993 Toyota Crown Majesta
#1
Driver School Candidate
Thread Starter
Need assistance - TRAC codes 48 and 51 - 1993 Toyota Crown Majesta
Hi All,
I have a 1993 Toyota Crown with 1UZ engine and 12,000 miles (very low miles!) which is currently giving me some trouble. I have both TRAC off and TRAC on lights engaged on the dash as well as a warning telling me to check engine, therefore I've jumped the pins to diagnose the TRAC system and received these two error codes - 48 and 51
48 - Sub-throttle position sensor signal is 4.3V or higher, or sub-throttle position sensor signal is 0.2V or lower when idle switch is OFF
51 - Problem in engine control system
Current issues are:
Hunting idle on startup
High Idle
Engine bogs/hesitates when gas pedal is blipped, but gas pedal being steadily depressed is okay
Slow Acceleration, can't even go up car ramps unless I get a running start
Things I've done thus far:
Replace IACV
Replace O2 sensors
Replace fuel filter
Tested ignition coils (resistance tested fine per the manual)
Pulled the ECU and inspected for any leakage or swollen capacitors but none were found
I also bought a used TPS to replace the sub-TPS (TPS furthest away from intake manifold but this didn't seem to fix the issue. However, now that I think about it I may not have lined up the sensor correctly).
I plan on pulling the throttle body to give it a good cleaning.
I'm a bit stumped that I can't solve this problem. Does anyone know of anything else I can test or replace?
I have a 1993 Toyota Crown with 1UZ engine and 12,000 miles (very low miles!) which is currently giving me some trouble. I have both TRAC off and TRAC on lights engaged on the dash as well as a warning telling me to check engine, therefore I've jumped the pins to diagnose the TRAC system and received these two error codes - 48 and 51
48 - Sub-throttle position sensor signal is 4.3V or higher, or sub-throttle position sensor signal is 0.2V or lower when idle switch is OFF
51 - Problem in engine control system
Current issues are:
Hunting idle on startup
High Idle
Engine bogs/hesitates when gas pedal is blipped, but gas pedal being steadily depressed is okay
Slow Acceleration, can't even go up car ramps unless I get a running start
Things I've done thus far:
Replace IACV
Replace O2 sensors
Replace fuel filter
Tested ignition coils (resistance tested fine per the manual)
Pulled the ECU and inspected for any leakage or swollen capacitors but none were found
I also bought a used TPS to replace the sub-TPS (TPS furthest away from intake manifold but this didn't seem to fix the issue. However, now that I think about it I may not have lined up the sensor correctly).
I plan on pulling the throttle body to give it a good cleaning.
I'm a bit stumped that I can't solve this problem. Does anyone know of anything else I can test or replace?
#2
Lexus Fanatic
There is a sub TPS? I can't find it in any diagram got a part number?
#3
Driver School Candidate
Thread Starter
It's essentially a second TPS on the 1UZ engines with TRAC. For instance, the # on mine is 89452-50020. From what I can tell it's the same as a regular TPS but the plug is keyed slightly different so if you want to replace it with a regular TPS model you'll have to shave the plastic side off so it'll fit.
#4
Moderator
There were many Crowns sent to junkyards due to the QAS capacitors issue,I must add.
#6
Moderator
#7
Pole Position
I have a 1993 Toyota Crown with 1UZ engine and 12,000 miles (very low miles!)
received these two error codes - 48 and 51
48 - Sub-throttle position sensor
51 - Problem in engine control system
Current issues are:
Hunting idle on startup
High Idle
Engine bogs/hesitates when gas pedal is blipped, but gas pedal being steadily depressed is okay
Slow Acceleration,
Pulled the ECU and inspected for any leakage or swollen capacitors but none were found
received these two error codes - 48 and 51
48 - Sub-throttle position sensor
51 - Problem in engine control system
Current issues are:
Hunting idle on startup
High Idle
Engine bogs/hesitates when gas pedal is blipped, but gas pedal being steadily depressed is okay
Slow Acceleration,
Pulled the ECU and inspected for any leakage or swollen capacitors but none were found
I had the same symptoms with the same codes on my 93 LS400 after about a year of owning it and I went nuts trying to track down the problem. I also looked inside the ECU and saw nothing wrong.....but unknown to me at that time, there was the problem. I eventually switched the ECU and everything came back to normal.
My suggestion would be; seeing how you can't see the caps leaking yet, have your ECU rebuilt with the good caps. Catch it before they leak and ruin the board, like mine eventually did and couldn't be repaired.
Got any pics of the 93 Crown?
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#8
Lexus Champion
Nice low mileage there.
I had the same symptoms with the same codes on my 93 LS400 after about a year of owning it and I went nuts trying to track down the problem. I also looked inside the ECU and saw nothing wrong.....but unknown to me at that time, there was the problem. I eventually switched the ECU and everything came back to normal.
My suggestion would be; seeing how you can't see the caps leaking yet, have your ECU rebuilt with the good caps. Catch it before they leak and ruin the board, like mine eventually did and couldn't be repaired.
Got any pics of the 93 Crown?
I had the same symptoms with the same codes on my 93 LS400 after about a year of owning it and I went nuts trying to track down the problem. I also looked inside the ECU and saw nothing wrong.....but unknown to me at that time, there was the problem. I eventually switched the ECU and everything came back to normal.
My suggestion would be; seeing how you can't see the caps leaking yet, have your ECU rebuilt with the good caps. Catch it before they leak and ruin the board, like mine eventually did and couldn't be repaired.
Got any pics of the 93 Crown?
#9
Driver School Candidate
Thread Starter
Nice low mileage there.
I had the same symptoms with the same codes on my 93 LS400 after about a year of owning it and I went nuts trying to track down the problem. I also looked inside the ECU and saw nothing wrong.....but unknown to me at that time, there was the problem. I eventually switched the ECU and everything came back to normal.
My suggestion would be; seeing how you can't see the caps leaking yet, have your ECU rebuilt with the good caps. Catch it before they leak and ruin the board, like mine eventually did and couldn't be repaired.
Got any pics of the 93 Crown?
I had the same symptoms with the same codes on my 93 LS400 after about a year of owning it and I went nuts trying to track down the problem. I also looked inside the ECU and saw nothing wrong.....but unknown to me at that time, there was the problem. I eventually switched the ECU and everything came back to normal.
My suggestion would be; seeing how you can't see the caps leaking yet, have your ECU rebuilt with the good caps. Catch it before they leak and ruin the board, like mine eventually did and couldn't be repaired.
Got any pics of the 93 Crown?
Thanks! I do see some cracking in the rubber seal surrounding the top. I'll put some sealant on it just in case and see if that helps
#10
Moderator
#11
Driver School Candidate
Thread Starter
Well just an update to the thread -
Replaced all the capacitors on the ECU. I'm not sure if I was blind when I initially looked at it but one was leaking quite bad and even caused corrosion on the board. Fortunately, I did what I could to clean much of the leakage up with isopropyl alcohol and replaced the capacitors. Car runs well now, just troubleshooting some unrelated minor miscellaneous things. Thank you everyone for your suggestions!
Replaced all the capacitors on the ECU. I'm not sure if I was blind when I initially looked at it but one was leaking quite bad and even caused corrosion on the board. Fortunately, I did what I could to clean much of the leakage up with isopropyl alcohol and replaced the capacitors. Car runs well now, just troubleshooting some unrelated minor miscellaneous things. Thank you everyone for your suggestions!
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sdls (08-22-20)
#12
Lexus Champion
Well just an update to the thread -
Replaced all the capacitors on the ECU. I'm not sure if I was blind when I initially looked at it but one was leaking quite bad and even caused corrosion on the board. Fortunately, I did what I could to clean much of the leakage up with isopropyl alcohol and replaced the capacitors. Car runs well now, just troubleshooting some unrelated minor miscellaneous things. Thank you everyone for your suggestions!
Replaced all the capacitors on the ECU. I'm not sure if I was blind when I initially looked at it but one was leaking quite bad and even caused corrosion on the board. Fortunately, I did what I could to clean much of the leakage up with isopropyl alcohol and replaced the capacitors. Car runs well now, just troubleshooting some unrelated minor miscellaneous things. Thank you everyone for your suggestions!
#13
Moderator
Well just an update to the thread -
Replaced all the capacitors on the ECU. I'm not sure if I was blind when I initially looked at it but one was leaking quite bad and even caused corrosion on the board. Fortunately, I did what I could to clean much of the leakage up with isopropyl alcohol and replaced the capacitors. Car runs well now, just troubleshooting some unrelated minor miscellaneous things. Thank you everyone for your suggestions!
Replaced all the capacitors on the ECU. I'm not sure if I was blind when I initially looked at it but one was leaking quite bad and even caused corrosion on the board. Fortunately, I did what I could to clean much of the leakage up with isopropyl alcohol and replaced the capacitors. Car runs well now, just troubleshooting some unrelated minor miscellaneous things. Thank you everyone for your suggestions!
#14
Driver School Candidate
Thread Starter
#15
Moderator